move implementation to ipmi file

Move the entrance point for the IPMI OEM handling to a separate file and
pass in the handler pointer via binding.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I4371ebee1c252ab6e9d8a7ff2389583919ecc996
diff --git a/cpld.cpp b/cpld.cpp
index 77d55d6..5e4fede 100644
--- a/cpld.cpp
+++ b/cpld.cpp
@@ -18,7 +18,7 @@
 
 #include "errors.hpp"
 #include "handler.hpp"
-#include "main.hpp"
+#include "ipmi.hpp"
 
 #include <cstring>